Half a croissant, on a plate, with a sign in front of it saying '50c'
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Window Blinds

Window blinds with white and black two sided slats
  [vote for,

In the summer you could have the white side of the slat reflect more solar energy, and in the winter you could use the black side to absorb more.

However, the heat gained in the winter might not be worth the reduced light reflected into the space.

myclob, Feb 28 2021

Absorbing light: Dark vs bright. https://sealevel.jp...vities/ts1enac1.pdf
Kid's experiment from NASA website. [doctorremulac3, Feb 28 2021]

US20110155331 https://patents.goo.../US20110155331A1/en
A dual purpose Venetian blind for assisting in cooling and/or heating an adjacent room by providing slats with one side having a heat absorbing surface and the opposite side having a heat reflecting surface. [xaviergisz, Mar 01 2021]


       It's good. If you search for "blinds black on one side white on the other" there are newspaper articles dating back to 1978 touting this as an energy saving idea but you need to subscribe to see them.   

       [kdf] - The sun rises and sets. The sun only comes into my house for about 45 minutes, while the sun angle allows it to come through the slats. I don't raise and lower the shades every morning and night. And so a good portion of the light gets reflected outside of the hose, because we want privacy.   

       And so no. We don't own it once it comes inside the glass. A good portion gets bounced back outside the glass. More gets bounced outside the glass in the winter than we want, because out blinds are white. The fact that people outside the glass see white, means that the solar energy and light is getting bounced outside the glass to them. If we had two color slots, we could have the black facing the sun in the winter, and the white facing the sun in the summer.   

       [2 fries] You are right. I couldn't find any products on Amazon or other sites with black white slats.
myclob, Feb 28 2021

       //Once the sunlight gets through the glass - any mix of wavelengths - you own it.//   

       Except in California.   

       Or anywhere else, for that matter : you should really bone up on the "greenhouse effect" : it's not the visible-range radiation that "bounces around" inside : if that comes in the window and hits something reflective it can bounce right back out, again.
FlyingToaster, Feb 28 2021

       You are right. We could test it very easily.   

       However, "if it doesn't exist now, then it is not a viable product" argument is wrong, pointless, and boring.   

       Almost every product could have come out earlier than it did.   

       This argument was proven wrong by every new invention.   

       re: "You’re not the first person to think of it, yet you can't find developed products. Why not?" Many "inventors" were able to get previously unsuccessful products to market. The demand for high performing buildings is greatly increasing, and will only continue in the future. Small improvements are more important as we try to deal with climate change, and energy efficiency. The USGBC is spreading best practices, and many people are sharing them. This might not offer much benefit, but it seems very easy to implement. Black paint seems just as readily available as white. When you open or close blinds you have two cords, but pulling either cord does essentially the same thing. If we have two cords to pull, why not have them do different things? One cord could be black, and the other could be white.
myclob, Feb 28 2021

       Suppose instead you made white window sash inserts -- one for the upper and another for the lower sash -- and stuck the lower one in that nether region outside the window but inside the screen, for the summer. Perhaps half of the sunlight gets reflected away.   

       In the winter you remove them and let the light in.
whatrock, Feb 28 2021

       [whatrock] That is a good idea too, and probably isn't mutually exclusive. In order to get green building points, there is a whole category for innovation within the USGBC rating system. It seems like someone should try it out and report if it is worth it or not...
myclob, Feb 28 2021

       The USGBC says one of it's guiding principals is to Promote revolutionary and evolutionary models that produce robust triple bottom line prosperity (planet, people, and profit).   

       The "revolution" and "evolution" is talking about both big and small changes.   

       I understand that this is not a big sexy change, but perhaps a bunch of small improvements equal one large change. In Denver the sun is there almost all the time. It would be nice to harvest or reflect more of it, depending on my needs.   

       Also, I understand that not very many people use black window blind slats.
myclob, Feb 28 2021

       //Once the sunlight gets through the glass - any mix of wavelengths - you own it. You can use shades to keep it dark in the room, keep the carpets and upholstery from fading, maybe - but it’s not going to make a difference in your heating and cooling costs.//   

       No. Interior window treatments are common energy conservation measures and are the simplest and most cost effective way to reduce energy consumption. I know, I used to do building envelope heat flow calculations for architects with my little consulting business when I was a teenager. Hundreds of houses and buildings in the Bay Area are very energy efficient because of me. I don't like to use the word hero but, well...   

       //Then riddle me this, Batman: You’re not the first person to think of it, yet you can't find developed products. Why not?//   

       Black on one side slats facing the sun would get hotter by maybe 20 degrees radiating more heat into the house than the white side, but as Batman might tell you, black blinds wouldn't be esthetically pleasing to most folks. Black isn’t a popular color to paint or accessorize houses.   

       Good thinking though myclob. [+]
doctorremulac3, Feb 28 2021

       Words and facts have meaning to some people.   

       Here's an experiment designed for elementary school kids. (link) Maybe you can have a juice box after.   

       But don't bother reporting the results. I know how this one turns out.
doctorremulac3, Feb 28 2021

       There's a lot of factors that affect the temperature of a structure's interior. Climate zone, micro-climate, slab on grade or raised floor, R value of the insulation, infiltration base, (gaps in the envelope like around wall penetrations like doors and windows) shading like your overhang, orientation to the sun etc but probably the biggest is glazing.   

       I used to specify low emissivity coatings as one of my tools to get a building to comply with Title-24 energy compliance regulations. Emissivity is the abilty of materials to radiate heat. Reflective stuff has low E, dark stuff has high E.   

       The U-value of the glass is also another big factor which is why double glazing is pretty standard now.   

       God how boring. No wonder I gave the business away to a relative and got into music to make a living.
doctorremulac3, Mar 01 2021

       Metal colored would be more effective.
Voice, Mar 01 2021

       //got into music to make a living// Yes I can see it now!   

       Scene: on stage in a stadium, Dr. and the Remulacs strike into their best-loved hit while the crowd of 50,000 marketing analysts and building fitters go wild:
<electric guitar riffs> chugga chugga chugga pop!
The U-value of glass
hup! hup! hup! hup!
is another big factor
<crowd screams so loud they drown out the music>
which is why double glay-ay-ay-ay-zing
is pretty a maaaaaaaaaaaaaaaaaaaaaaaay
<wild guitar solo>
<screaming into mic>it's pretty standard now
danna doo ee ooo boo wappa eeeeeee...
pocmloc, Mar 01 2021

pertinax, Mar 01 2021

       [Doc]'s right. Blinds are terrible at controlling convection currents out a single pane uncoated hole in the wall. The recommendations are for well fitting (seal around window edges), full length double lined curtains. Overheating is a different story, planting and seasonal shade cloths.   

       Of course, the option of increasing power usage is always an option, if it is a green enough source. Go SMRs.   

       Then again, does the human body need a cold cycle at night. The weather certainly does.
wjt, Mar 01 2021

       Poc, I remember that! Good show. At the meet-n- greet backstage with the radio stations, record store reps and magazine reporters we all talked about HVAC efficiency and ductwork static pressure. The groupies all brought their ductulators to be autographed. Ahh memories.
doctorremulac3, Mar 01 2021

       Well, my two cents, it was a great idea, just maybe slightly baked. Certainly NWKTE.
blissmiss, Mar 02 2021


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